In the Atlantic Hurricane Gilbert went from 960 mb to 888 mb in a 24 hour period for a 3 mb/hr pressure drop. The winds went from 57 to 82 m/s (110 kt to 160 kt, 127 mph to 184 mph) in that 24 hour period. And Hurricane Beulah in 1967 underwent a 6.33 mb/hr drop over a six hour period.